dt-bindings: dmaengine: Introduce RZN1 DMA compatible

Just like for the NAND controller that is also on this SoC, let's
provide a SoC generic and a more specific couple of compatibles for the
DMA controller.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20220427095653.91804-4-miquel.raynal@bootlin.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/dma/snps,dma-spear1340.yaml

@@ -15,7 +15,13 @@ allOf:
 
 properties:
   compatible:
-    const: snps,dma-spear1340
+    oneOf:
+      - const: snps,dma-spear1340
+      - items:
+          - enum:
+              - renesas,r9a06g032-dma
+          - const: renesas,rzn1-dma
+
 
   "#dma-cells":
     minimum: 3